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PubMed2004

[Thromboelastography in liver transplantation, a comparison with conventional laboratory tests].

BACKGROUND: The aim of our study was to compare the results of conventional tests and thromboelastography during liver transplantation and to determine their importance for blood loss. METHODS AND RESULTS: Thromboelastography and conventional laboratory tests were undertaken in 25 patients at the end of the anhepatic phase. Transfusion requirements correlated significantly only with prothrombin time and reaction time, R. These two tests likewise correlated significantly one with the other. CONCLUSIONS: Lowered plasma levels of coagulation factors of the prothrombin complex influenced the blood losses in our patients. While not replacing conventional tests, thromboelastography can serve as an additional test for monitoring acute changes in hemostasis.

Adolescent↗
PubMedDate not supplied

Essential thrombocythemia and epidural analgesia in the parturient. Does thromboelastography help?

BACKGROUND AND OBJECTIVES: It is often considered that essential thrombocythemia contraindicates placement of an epidural catheter because of the danger of epidural hematoma. Thromboelastography offers a possible means of determining the appropriateness of epidural analgesia in a patient with this disorder. METHODS: A pregnant woman with essential thrombocythemia and a history of spontaneous abortions was evaluated by thromboelastography at 38 weeks of gestation to determine the safety of using epidural analgesia for labor pain management. On the basis of the thermoelastography findings, the patient was given epidural analgesia with bupivacaine and fentanyl during her labor. RESULTS: The patient experienced good pain relief, delivered a healthy infant vaginally, and suffered no complications. CONCLUSIONS: Thromboelastography may be a useful diagnostic test in determining the suitability of regional techniques for labor analgesia in parturients with essential thrombocythemia. However, success in one patient does not prove the general safety of this approach.

Adult↗
PubMed2001

Analysis of coagulation changes associated with supraceliac aortic crossclamping using thromboelastography.

INTRODUCTION: The etiology of the coagulation changes seen with supraceliac (SC) aortic crossclamping (AXC) remains controversial; both primary fibrinolysis and clotting factor consumption have been implicated. The cause of these changes was investigated with thromboelastography (TEG), a test that measures the viscoelastic properties of thrombus to dynamically assess coagulation and fibrinolysis. METHODS: Eight pigs underwent SC AXC for 30 min; 5 pigs undergoing 30 min of infrarenal (IR) aortic clamping served as controls. Blood was drawn before AXC, before unclamping, and 5 and 60 min after unclamping. Thromboelastography and standard coagulation tests [prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen, and platelet count] were performed. Measured TEG parameters included fibrinolytic index (a measure of fibrinolysis), r value (a reflection of intrinsic coagulation cascade activity), and the alpha angle and K values (measures of the speed of solid clot formation). Repeated measures ANOVA and t test were used for statistical analysis. RESULTS: There was no difference in the fibrinolytic index at any time point between the two groups. Increased activity of the intrinsic coagulation cascade during SC clamping was reflected by a lower R value just before unclamping (12.6 +/- 3.0 vs 20.0 +/- 3.0, P = 0.048) compared to IR AXC. Decreased speed of solid clot formation was noted 5 min after unclamping in the SC group but not the IR group [as defined by an increased K value (ANOVA, P = 0.010) and a decreased alpha angle value (ANOVA, P = 0.005)]. Fibrinogen levels were lower in the SC than in the IR group 5 (P = 0.013) and 60 min after unclamping (P = 0.02), but PT, PTT, and platelets did not differ between the groups at any time points. CONCLUSIONS: Thirty minutes of SC AXC does not result in fibrinolysis. There is increased clotting activity during SC clamping followed by decreased speed of clot formation and decreased fibrinogen levels after unclamping. These changes are consistent with clotting factor consumption.

Animals↗
PubMed1998

The usefulness of celite-activated thromboelastography for evaluation of fibrinolysis.

PURPOSE: Although thromboelastography is useful for measuring both coagulability and fibrinolysis, it takes about two hours to measure all parameters including fibrinolytic rate. The present study aimed to investigate the usefulness of celite-activated thromboelastography (TEGc) to evaluate fibrinolytic status in non-cardiac surgery. METHODS: Whole blood samples were obtained from 30 patients for non-cardiac surgery, and used for measurements of both native TEG (TEGn) and TEGc. The final concentration of 1% (w/v) celite was used for TEGc. RESULTS: Time for measurement of the fibrinolytic rate (FR) of TEGc in patients (56.7 +/- 4.0 min) was less than half that of FR of TEGn (123.3 +/- 15.6 min) (P < 0.05), suggesting a more rapid assessment of fibrinolytic status. A linear relationship was observed between FR values of TEGc and those of TEGn (r = 0.93, P < 0.0001), suggesting the usefulness of the fibrinolytic parameter of TEGc. CONCLUSION: TEGc is a useful technique for a more rapid assessment of fibrinolytic status.

Adult↗
PubMed1997

Platelet concentrate effects on thromboelastography.

OBJECTIVE: This study evaluated platelet effects on thromboelastography to determine how morphologically abnormal platelets affected native whole blood analysis. DESIGN: Prospective, controlled comparison. SETTING: Tertiary care university hospital. PARTICIPANTS: Volunteer cardiac surgery patients. INTERVENTIONS: Fresh platelets were obtained from volunteers and were either treated normally or cryodisrupted with liquid nitrogen. Fresh platelets, liquid nitrogen-treated platelets, or an equivalent quantity of the patient's blood were added to whole blood samples obtained from cardiac surgery patients before heparinization. Thromboelastographic parameters sensitive to platelet effects were measured in each of the three groups. MEASUREMENTS AND MAIN RESULTS: Maximum amplitude and alpha-angle significantly increased in the two groups receiving added platelets. There were no differences between the fresh platelet and the liquid nitrogen-treated platelet groups (Student's paired t-test). The R-time decreased significantly in both platelet-treated groups compared with the group that did not receive additional platelets. CONCLUSIONS: Viscoelastic changes in whole blood coagulation after the addition of platelet concentrates are not dependent on morphologically intact or functionally normal platelets. This in vitro study predicts that transfusion of poorly preserved platelet concentrates as well as fresh platelets would increase clot strength on thromboelastography if the recipient's blood were tested immediately after administration.

Blood Coagulation↗
PubMed2003

The effects of hydroxyethyl starch solutions on thromboelastography in preoperative male patients.

BACKGROUND: Hydroxyethyl starches (HES) have been shown to decrease clot strength and to increase coagulation times assessed by thromboelastography (TEG). HES with minimal anticoagulant side-effects is beneficial for plasma volume expansion in the perioperative setting. A comparison of the in vivo effects of high, middle and low molecular weight HES solutions on TEG variables has not been performed so far. METHODS: Blood was obtained before and after intravenous infusion (10 ml kg-1) of either saline, HES 70/0.5/4 (molecular weight in kDa/degree of substitution/C2:C6 ratio), HES 130/0.4/9, HES 200/0.6/9.4, or HES 450/0.7/4.6 in 50 otherwise healthy patients. Thromboelastography was performed in 360 micro l of 1% celite activated citrated whole blood after recalcification. RESULTS: HES 450/0.7/4.6 prolonged reaction time indicating impairment of the plasmatic coagulation system. TEG parameters indicative for platelet function, including angle alpha, maximum amplitude and coagulation time, deteriorated after infusion of HES 450/0.7/4.6 and HES 70/0.5/4. HES 200/0.6/9.4 and HES 130/0.4/9 impaired platelet contribution to hemostasis only partially, decreasing two or one TEG platelet parameters, respectively. CONCLUSION: Infusion of HES 450/0.7/4.6 compromises TEG parameters more than the other solutions tested, whereas HES 130/0.4/9 has the smallest effect. Further outcome-related studies are needed in order to assess the clinical relevance of our findings.

Adult↗
PubMed2000

Evaluation of the contribution of platelets to clot strength by thromboelastography in rabbits: the role of tissue factor and cytochalasin D.

UNLABELLED: The contribution of platelets and soluble clotting components to clot strength has been the focus of several clinical studies using thromboelastography; it would, therefore, be beneficial to develop an animal model with which to mechanistically approach hemostatic disorders. Thus, we proposed to determine if the contribution of platelet function (G(P), dyne/cm(2)) and soluble components of the coagulation pathway to total clot strength (G(T)) in rabbits were similar to those in humans. Blood was sampled from the ear arteries of conscious rabbits (n = 12); 350 microL of the blood was placed in a thromboelastograph. Ten microliters of normal saline, cytochalasin D (an inhibitor of microtubule function, 10 microM final concentration), or tissue factor (a potent stimulator of platelet function, 0.00625% final concentration) was added to the blood sample, and thromboelastography performed for 1 h. The G(T) (mean +/- SD) was significantly (P < 0.001) different among samples exposed to normal saline, cytochalasin D, or tissue factor, with G(T) values of 7238 +/- 1432, 937 +/- 372, and 16,556 +/- 3314, respectively. G(P) was responsible for 87% and 94% of G(T) in the absence or presence of tissue factor, respectively. G(P) did not significantly correlate with platelet concentration in the absence or presence of tissue factor. The contribution of G(P) to G(T) is similar to that observed in humans. IMPLICATIONS: Rabbits may serve as a model of hemostasis that closely approximates human situations to mechanistically determine the etiology of coagulopathy. The contribution of platelet function to total clot strength is similar to that observed in humans.

Animals↗
PubMed1995

Effects of the platelet-activating factor receptor antagonist WEB 2086 on whole blood coagulation and fibrinolysis in a thromboelastography assay.

The effects of WEB 2086 on human blood coagulation and fibrinolysis were studied in vitro using computerized thromboelastography and native whole blood. WEB 2086 (3.0, 30, 150, and 300 microM) had no apparent effect on the split point (SP), reaction time (R) and lysis of the clot. The biKoatugulierung time (K) was prolonged, the angle (alpha) and maximum amplitude (MA) were diminished, and the overall coagulation index (TEG index) was smaller. SP and R indicate onset of coagulation with the formation of fibrin strands, suggesting that WEB 2086 had no effect on the plasma factors. Since the Lysis parameter reflects fibrinolysis, WEB 2086 had no demonstrable fibrinolytic activity. K, alpha and MA involve platelet function and the integrity of fibrin; the fact that these factors were affected to the exclusion of SP and R suggests an effect largely on platelets. There was lack of a dose-response relationship at this concentration range (3.0-300 microM), probably due to saturation of PAF receptors even at the lowest effective concentration. These findings are consistent with the known effects of WEB 2086 on platelet function and suggest that thromboelastography may be a useful tool in the study of the activity of PAF receptor antagonists on coagulation profiles. Furthermore, since WEB 2086 is a highly specific PAF receptor antagonist devoid of intrinsic activity, and the samples used were not treated with exogenous PAF, these results suggest that endogenous PAF may play a significant role in the normal clotting mechanism.

Azepines↗
PubMed1997

In vitro evaluation of the effect of profound haemodilution with hydroxyethyl starch 6%, modified fluid gelatin 4% and dextran 40 10% on coagulation profile measured by thromboelastography.

Synthetic colloids have been implicated as a cause of coagulopathy when administered in large quantities. The effect of profound haemodilution (50%) on coagulation profile was measured in vitro by thromboelastography. Blood samples were taken from 11 ASA grade 1 patients prior to induction of anaesthesia for elective surgery. Each sample was simultaneously tested in four different preparations: undiluted blood (control sample); blood diluted with hydroxyethyl starch 6%; blood diluted with modified fluid gelatin 4%; blood diluted with dextran 40 10%. There was a significant decrease in reaction time in the preparations treated with hydroxyethyl starch 6% and modified fluid gelatin 4%, reflecting activation of initial fibrin formation. A significant increase in clot formation time was noted in the hydroxyethyl starch 6%-treated preparations. There was also a significant decrease in clot formation rate and maximum amplitude in the hydroxyethyl starch 6% group. Clot formation time, clot formation rate and maximum amplitude did not change in the modified fluid gelatin 4% group. Profound haemodilution with dextran 40 10% exerted extreme effects on the measured variables, very often resulting in a straight line on the thromboelastography profile.

Blood Coagulation↗
PubMed1998

Preoperative evaluation and postoperative prediction of hemostatic function with thromboelastography in patients undergoing redo cardiac surgery.

BACKGROUND: Patients who receive cardiac procedures, in particular "redo" ones, often suffer complications from massive bleeding, largely due to bypass-induced coagulopathies. Cardiopulmonary bypass (CPB) may cause damage of the blood components, both in terms of quality and quantity. In order to investigate the qualitative changes of blood constituents with special regard to coagulation resulting from the complex insult of previous cardiac surgery, thromboelastography (TEG) was used to analyze the whole clotting process. METHODS: Seventy-four patients who underwent cardiac surgery with CPB were prospectively studied. Of them, 32 patients received "redo" cardiac surgery. Blood samples for routine laboratory coagulation tests (RCT) and TEG examination were drawn before and after cardiopulmonary bypass. Clinically significant bleeding was defined if the chest tube drainage was greater than 100 ml/h for 3 consecutive h or greater than 300 ml in 1 h during the first 8 h after surgery. Prebypass and postbypass coagulation parameters were compared and the percentage of accuracy, false positive and false negative rate were deduced from calculation. RESULTS: In the TEG tracings, preoperative alpha angle and maximum amplitude were significantly decreased in the "redo" group when compared with primary group, indicating less competent platelet function and platelet-fibrin interaction. Lower platelet count was also found by conventional coagulation tests in "redo" patients. Postoperatively, higher percentage of excessive hemorrhage was also noted in the "redo" group (42.8% vs. 27.5% in primary group). However, a much lower predictive accuracy was found in "redo" patients in comparison with primary cardiac patients (53.5% vs. 90%). CONCLUSIONS: We concluded that thromboelastography failed to predict postoperative hemorrhage in "redo" cardiac patients and the graphic recordings derived could not be treated as a guide of transfusion therapy. We thought that inferior preoperative hemostatic status and severer coagulopathy might be responsible for the differences between "redo" and primary cardiac patients.

Adult↗
PubMed2002

The effect of anesthetic techniques on hemostatic function in arthroscopic surgery: evaluation by thromboelastography.

BACKGROUND: Anesthetic techniques are known to affect blood hemostasis, which may be responsible for the pathogenesis of postoperative venous thromboembolism. The purpose of this study was to evaluate the effect of general and spinal anesthesias on blood hemostasis using thromboelastography. METHODS: Forty patients undergoing arthroscopic knee surgery were enrolled for study and randomly allocated to one of two groups, to receive either general (GA; n = 20) or spinal anesthesia (SA; n = 20). In addition to thromboelastography, prothrombin and activated partial-thromboplastin time, and haematocrit and platelet count were also examined concurrently. Blood was sampled and examined before anesthesia to provide the baseline data (Time 1). Three more evaluations were performed at different time, i.e., twenty minutes after induction of anesthesia and just prior to skin incision (Time 2), thirty minutes after skin incision (Time 3), and three hours after surgery (Time 4). RESULTS: There were no intra- or inter-group differences noted as comparing the measured parameters obtained prior to, during, or three hours after surgery. CONCLUSIONS: From the present study, we do not find any individual anesthetic technique which would have effect on the hemostasis of patients who received diagnostic arthroscopic surgery.

Anesthesia, General↗
PubMed1992

[Analysis of blood coagulation and fibrinolysis in rheumatoid arthritis using the urokinase activated thromboelastography].

The urokinase activated thromboelastography is useful for the analysis of blood coagulation and fibrinolysis in rheumatoid arthritis (RA). In 43 RA patients without extraarticular symptoms (mean year old +/- SD = 50.3 +/- 10.9) and 20 healthy control subjects (mean year old +/- SD = 49.5 +/- 13.8, which is not significant), we have examined reaction time (r), coagulation time (k), r+k, maximal amplitude (ma), lysis time (LT) of the urokinase (final density = 85U/ml) activated platelet rich plasma thromboelastography. In RA patients r, k, r+k are shorter, ma is larger, LT is longer than in control subjects. Especially, k, ma and LT are remarkably statistically significant. these findings suggest that most of RA patients have hypercoagulability and/or prolongation of lysis time simultaneously, k, ma and LT are pathophysiologically important.

Adult↗
PubMed1994

Action of Calloselasma rhodostoma (Malayan pit viper) venom on human blood coagulation and fibrinolysis using computerized thromboelastography (CTEG).

The effects of Malayan pit viper (Calloselasma rhodostoma) venom on human blood coagulation and fibrinolysis were studied in vitro using computerized thromboelastography. At low concentrations the venom had a coagulant effect shown by faster onset of the coagulation process (shortened SP and R), faster progress of the clot (increased angle and shortened K), and increased coagulation (TEG) index. The maximum amplitude (MA) was not affected, suggesting that the venom had no apparent effect on platelet function; and clot lysis was similar to that in the controls, suggesting that there was no primary fibrinolytic activity. At higher concentrations the venom had anticoagulant effects, SP and R were progressively shortened, but there was poor/no progress in the clot formed, evident from prolonged or absent K, diminished MA and reduced angle. These results show that C. rhodostoma venom has both coagulant and anticoagulant actions. The coagulant action may be due to Factor X activator predominance at low concentrations, while the anticoagulant action could be due to ancrod action. TEG is able to demonstrate the dual effect of this venom, previously described as a paradox, and may be a useful tool in the diagnosis and monitoring of envenomation patients.

Anticoagulants↗
PubMed1995

Anticoagulant effects of Pseudechis australis (Australian king brown snake) venom on human blood: a computerized thromboelastography study.

The crude venom of Pseudechis australis exhibited a dose-dependent anticoagulant action on human blood in vitro using computerized thromboelastography. Clot progress parameters (K and alpha) were affected at low dose levels which had no effect on onset of coagulation parameters (SP, R). At high dose levels there was total anticoagulant effect, but in all cases there was no evidence of fibrinolytic activity. These results generally agree with the known effects of this venom on coagulation in vivo, and further support our earlier suggestion that TEG may be a useful, one-step tool in the diagnosis and monitoring of the progress of envenomation patients.

Anticoagulants↗
PubMedDate not supplied

Influence of ketorolac tromethamine on clot elastic strength in humans as assessed by thromboelastography.

STUDY OBJECTIVE: To evaluate the effect of ketorolac tromethamine on coagulation using thromboelastography (TEG). DESIGN: TEGs were performed in each patient before and after ketorolac administration. Each patient's predrug results were used as control measurements for comparison with the postdrug results. SETTING: Medical center surgical unit. PATIENTS: Twenty ASA physical status I and II patients undergoing minor elective surgery; 12 healthy volunteers. INTERVENTIONS: TEGs were performed in all subjects before and 60 minutes after the intramuscular (IM) administration of ketorolac tromethamine 60 mg. Ten surgical patients were studied in the intraoperative period, and 10 surgical patients were studied in the postoperative period. The 12 healthy volunteers did not undergo a surgical procedure. MEASUREMENTS AND MAIN RESULTS: Specific parameters assessed from the TEGs were reaction time (R time), coagulation time (RK time), clot formation rate (angle of deflection), and maximum clot strength (maximum amplitude of deflection). Ketorolac administration did not cause statistically significant changes in these parameters in any of the three groups studied. CONCLUSIONS: IM administration of ketorolac tromethamine 60 mg did not significantly alter the speed of formation or viscoelastic strength of clots as measured by TEG. These results provide additional support for prior clinical studies confirming the safety of ketorolac administration in the perioperative period.

Adult↗
PubMedDate not supplied

Thromboelastography and Sonoclot analysis in the healthy parturient.

STUDY OBJECTIVE: To compare values for two whole blood viscoelastic coagulation tests, thromboelastography (TEG) and Sonoclot analysis (Sonoclot R Coagulation Analyzer, Sienco, Inc., Morrison, CO), between healthy parturients and nonparturients. DESIGN: Prospective study. SETTING: University hospital. PATIENTS: 41 healthy, nonpregnant females and full-term nonlaboring and laboring parturients. INTERVENTIONS: Blood samples for TEG and Sonoclot analysis were taken from all patients. TEG tracings were analyzed for reaction time (R), coagulation time (RK), the difference between RK and R (K), clot formation rate (alpha degree), and maximum amplitude (MA) values. Sonoclot tracings were analyzed for onset, rate increases, peak, and rate decreases values. MEASUREMENTS AND MAIN RESULTS: All TEG values were significantly different between nonpregnant females and parturients (p < 0.05). Sonoclot analysis showed that the parturients had a significantly decreased onset and increased primary slope (rate increases) in comparison to the nonpregnant females (p < 0.05). CONCLUSION: The differences found in the parturients reflect a hypercoagulable state. If these tests are to be used in evaluating obstetric patients, the results should be compared with values obtained for healthy parturients, not healthy nonparturients.

Blood Coagulation Tests↗
PubMed1993

Comparison of thromboelastography to bleeding time and standard coagulation tests in patients after cardiopulmonary bypass.

This prospective study of 36 adult patients undergoing cardiopulmonary bypass (CPB) was conducted to determine the utility of thromboelastography (TEG) versus platelet studies (bleeding time, platelet count, mean platelet volume) and standard coagulation tests (prothrombin time, activated partial thromboplastin time, fibrinogen) to more effectively discriminate patients likely to benefit from platelet or fresh frozen plasma (FFP) transfusion. Although the sensitivities of the bleeding time (71.4%) and platelet count (100%) were similar to the TEG (71.4%), the specificity (89.3%) of the TEG was greater than that of the bleeding time (78.5%) and platelet count (53.6%). Seven patients experienced clinically significant hemorrhage; 5 (71.4%) had an abnormal TEG. Three of 8 (38%) other patients with an abnormal TEG had no abnormal bleeding. Only 2 of 27 (7.4%) patients with a normal TEG had abnormal bleeding requiring platelet or FFP transfusion. Therefore, it is suggested that post-CPB patients with a normal TEG should not receive platelet or FFP transfusions empirically. If excessive bleeding is noted in a patient with a normal TEG, this suggests a surgically correctable etiology. Data from this series suggest that patients displaying an abnormal TEG appear to be at increased risk for hemorrhage; therefore, appropriate blood product support should be initiated at the first sign of accelerated bleeding.

Adolescent↗
PubMed1993

An assessment of the duration of cephapirin-induced coagulation abnormalities as measured by thromboelastography.

Cephalosporin antibiotics are used prophylactically in cardiothoracic surgery to prevent postoperative infection. In 30 patients undergoing primary elective coronary artery bypass grafting, the whole blood coagulation system was prospectively evaluated before, and 10 and 30 minutes after administration of 1 g of cephapirin (Cefadyl, Bristol Laboratory, Evansville, IN). All patients had normal preoperative coagulation studies and had not received anticoagulant or antiplatelet therapy within 7 days of surgery. At 10 minutes after cephapirin administration, 23 of 30 patients had a significant change in all phases of whole blood coagulation as monitored by thromboelastography (TEG). Thirty minutes after cephapirin administration there was no statistical difference compared with the baseline TEG. It is concluded that cephapirin can cause a significant but transient change in the viscoelastic properties of blood. Coagulation parameters of the TEG should be measured prior to cephapirin administration to prevent errors in establishing baseline values prior to cardiopulmonary bypass.

Blood Coagulation↗